Unfalsifiable audit logs for a blockchain

ABSTRACT

An example operation may include one or more of connecting to a blockchain configured to store transactions executed by the participating node, executing a transaction to produce a transaction trail, assigning a transaction identifier (ID) to the transaction, generating a transaction tag based on the transaction ID, and sending to the blockchain the transaction tag and the transaction trail to be entered into the blockchain.

TECHNICAL FIELD

This application generally relates to blockchain technology, and moreparticularly, to unfalsifiable audit logs for a blockchain.

BACKGROUND

In today's world, blockchains are used for a wide variety ofapplications. A blockchain is a Cryptographic Distributed Ledger (CDL).A distributed ledger is a ledger that is replicated in whole or in partto multiple computers. The CDL can have at least some of theseproperties: irreversibility (once a transaction is recorded, it cannotbe reversed), accessibility (any party can access the CDL in whole or inpart), chronological and time-stamped (all parties know when atransaction was added to the ledger), consensus based (a transaction isadded only if it is approved, typically unanimously, by parties on thenetwork), verifiability (all transactions can be cryptographicallyverified).

A distributed ledger is a continuously growing list of records thattypically apply cryptographic techniques such as storing cryptographichashes relating to other blocks. A blockchain is one common instance ofa distributed ledger and may be used as a public ledger to storeinformation. Although, primarily used for financial transactions, ablockchain can store various information related to goods and services(i.e., products, packages, status, etc.). A decentralized schemeprovides authority and trust to a decentralized network and enables itsnodes to continuously and sequentially record their transactions on apublic “block”, creating a unique “chain” referred to as a blockchain.Cryptography, via hash codes, is used to secure an authentication of atransaction source and removes a central intermediary. A blockchain is adistributed database that maintains a continuously-growing list ofrecords in the blockchain blocks, which are secured from tampering andrevision due to their immutable properties. Each block contains atimestamp and a link to a previous block. A blockchain can be used tohold, track, transfer and verify information. Since a blockchain is adistributed system, before adding a transaction to the blockchainledger, all peers need to reach a consensus status.

Because of the distributed nature of the blockchain, it can be used tostore transaction trails that may be used later for auditing purposes.However, an audit trail stored on the blockchain may reveal or leaksensitive information about the transaction, because the blockchain ispublicly readable or at least readable by the entities that run theblockchain. Additionally, a blockchain entity can store several trailsfor the same transaction so the entity can later present one favorabletrail depending on the situation. In general, existing blockchainsolutions leak various amounts of information about the transactions.

Accordingly, what is needed is an efficient automated method for storingtransaction trails in a blockchain in a way that the audit trail storedin the blockchain may not reveal any information about the transactionand that any of the blockchain entities may not be able to store severaltrails for the same transaction.

SUMMARY

One example embodiment may provide a method that includes one or more ofconnecting, by a participating node, to a blockchain configured to storetransactions executed by the participating node, executing, by theparticipating node, a transaction to produce a transaction trail,assigning, by the participating node, a transaction identifier (ID) tothe transaction, generating, by the participating node, a transactiontag based on the transaction ID, and sending to the blockchain, by theparticipating node, the transaction tag and the transaction trail to beentered into the blockchain.

Another example embodiment may provide a system that includes aprocessor and memory, wherein the processor is configured to perform oneor more of connect to a blockchain configured to store transactionsexecuted by a participating node, execute a transaction to produce atransaction trail, assign a transaction identifier (ID) to thetransaction, generate a transaction tag based on the transaction ID, andsend, to the blockchain, the transaction tag and the transaction trailto be entered into the blockchain.

A further example embodiment may provide a non-transitory computerreadable medium comprising instructions, that when read by a processorof a participating node, cause the processor to perform one or more ofconnecting to a blockchain configured to store transactions executed bythe participating node, executing a transaction to produce a transactiontrail, assigning a transaction identifier (ID) to the transaction,generating a transaction tag based on the transaction ID, and sending tothe blockchain the transaction tag and the transaction trail to beentered into the blockchain.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a system diagram for generation of unfalsifiableaudit logs in a blockchain, according to example embodiments.

FIG. 2A illustrates an example peer node blockchain architectureconfiguration for generation of unfalsifiable audit logs for ablockchain, according to example embodiments.

FIG. 2B illustrates an example peer node blockchain configuration,according to example embodiments.

FIG. 3 is a diagram illustrating a permissioned blockchain network,according to example embodiments.

FIG. 4A illustrates a flow diagram of an example method of generation ofunfalsifiable audit logs, according to example embodiments.

FIG. 4B illustrates a flow diagram of an example method of processing ofthe transaction tag for a transaction trail to be entered into ablockchain, according to example embodiments.

FIG. 5A illustrates an example physical infrastructure configured toperform various operations on the blockchain in accordance with one ormore operations described herein, according to example embodiments.

FIG. 5B illustrates an example smart contract configuration amongcontracting parties and a mediating server configured to enforce smartcontract terms on a blockchain, according to example embodiments.

FIG. 6 illustrates an example computer system configured to support oneor more of the example embodiments.

DETAILED DESCRIPTION

It will be readily understood that the instant components, as generallydescribed and illustrated in the figures herein, may be arranged anddesigned in a wide variety of different configurations. Thus, thefollowing detailed description of the embodiments of at least one of amethod, apparatus, non-transitory computer readable medium and system,as represented in the attached figures, is not intended to limit thescope of the application as claimed but is merely representative ofselected embodiments.

The instant features, structures, or characteristics as describedthroughout this specification may be combined in any suitable manner inone or more embodiments. For example, the usage of the phrases “exampleembodiments”, “some embodiments”, or other similar language, throughoutthis specification refers to the fact that a particular feature,structure, or characteristic described in connection with the embodimentmay be included in at least one embodiment. Thus, appearances of thephrases “example embodiments”, “in some embodiments”, “in otherembodiments”, or other similar language, throughout this specificationdo not necessarily all refer to the same group of embodiments, and thedescribed features, structures, or characteristics may be combined inany suitable manner in one or more embodiments.

In addition, while the term “message” may have been used in thedescription of embodiments, the application may be applied to many typesof network data, such as, packet, frame, datagram, etc. The term“message” also includes packet, frame, datagram, and any equivalentsthereof. Furthermore, while certain types of messages and signaling maybe depicted in exemplary embodiments they are not limited to a certaintype of message, and the application is not limited to a certain type ofsignaling.

Example embodiments provide methods, systems, non-transitory computerreadable media, devices, and/or networks, which provide for generationof unfalsifiable audit logs in a blockchain. The example embodimentsalso provide for a mechanism for generating a transaction tag based on aunique transaction ID.

The exemplary embodiments may use stored recorded transactions. Ablockchain is a distributed system, which includes multiple nodes thatcommunicate with each other. A blockchain operates programs calledchaincode (e.g., smart contracts, etc.), holds state and ledger data,and executes transactions. Some transactions are operations invoked onthe chaincode. In general, blockchain transactions typically must be“endorsed” by certain blockchain members and only endorsed transactionsmay be committed to the blockchain and have an effect on the state ofthe blockchain. Other transactions that are not endorsed aredisregarded. There may exist one or more special chaincodes formanagement functions and parameters, collectively called systemchaincodes.

Nodes are the communication entities of the blockchain system. A “node”may perform a logical function in the sense that multiple nodes ofdifferent types can run on the same physical server. Nodes are groupedin trust domains and are associated with logical entities that controlthem in various ways. Nodes may include different types, such as aclient or submitting-client node which submits a transaction-invocationto an endorser (e.g., peer), and broadcasts transaction-proposals to anordering service (e.g., ordering node). Another type of node is a peernode, which can receive client submitted transactions, commit thetransactions and maintain a state and a copy of the ledger of blockchaintransactions. Peers can also have the role of an endorser, although itis not a requirement. An ordering-service-node or an orderer is a noderunning the communication service for all nodes, and which implements adelivery guarantee, such as a broadcast to each of the peer nodes in thesystem when committing transactions and modifying a world state of theblockchain, which is another name for the initial blockchain transactionwhich normally includes control and setup information.

A ledger is a sequenced, tamper-resistant record of all statetransitions of a blockchain. State transitions may result from chaincodeinvocations (i.e., transactions) submitted by participating parties(e.g., client nodes, ordering nodes, endorser nodes, peer nodes, etc.).A transaction may result in a set of asset key-value pairs beingcommitted to the ledger as one or more operands, such as creates,updates, deletes, and the like. The ledger includes a blockchain (alsoreferred to as a chain) which is used to store an immutable, sequencedrecord in blocks. The ledger also includes a state database, whichmaintains a current state of the blockchain. There is typically oneledger per channel. Each peer node maintains a copy of the ledger foreach channel of which they are a member.

A chain is a transaction log which is structured as hash-linked blocks,and each block contains a sequence of N transactions where N is equal toor greater than one. The block header includes a hash of the block'stransactions, as well as a hash of the prior block's header. In thisway, all transactions on the ledger may be sequenced andcryptographically linked together. Accordingly, it is not possible totamper with the ledger data without breaking the hash links. A hash of amost recently added blockchain block represents every transaction on thechain that has come before it, making it possible to ensure that allpeer nodes are in a consistent and trusted state. The chain may bestored on a peer node file system (i.e., local, attached storage, cloud,etc.), efficiently supporting the append-only nature of the blockchainworkload.

The current state of the immutable ledger represents the latest valuesfor all keys that are included in the chain transaction log. Because thecurrent state represents the latest key values known to a channel, it issometimes referred to as a world state. Chaincode invocations executetransactions against the current state data of the ledger. To make thesechaincode interactions efficient, the latest values of the keys may bestored in a state database. The state database may be simply an indexedview into the chain's transaction log, it can therefore be regeneratedfrom the chain at any time. The state database may automatically berecovered (or generated if needed) upon peer node startup, and beforetransactions are accepted. As discussed above, the exemplary embodimentsmay use recorded blockchain transactions stored on a blockchain ledger.

According to the exemplary embodiments, a blockchain entity may producea unique tag from a transaction ID in a way that the tag does not revealthe transaction ID. This may be implemented using a keyed one-wayfunction. Then, the tag may be stored in the blockchain along with atransaction trail. The transaction trail may be either encrypted orstored using information theoretic hiding commitments that provide along term protection of the transaction. Because the tag is unique pertransaction ID (and participating entity), an auditor can check whetherthere is indeed only one trail stored in or committed to the blockchain.Because the tag does not reveal the transaction ID, all informationstored in the blockchain is protected. If the participating entity is tobe audited for a transaction at a later time, the participating entitymay be able to provide the tag for that transaction ID and prove thatthis is the correct tag for this transaction ID (using a cryptographiczero-knowledge proof) and provide the audit trail. The auditor can thencheck that there is the tag stored on the blockchain and there is only asingle trail for the transaction identified by the ID.

The example embodiments are directed to methods, devices, networks,non-transitory computer readable media and/or systems, which support ablockchain solution for generation of unfalsifiable audit logs inblockchains. Some of the benefits of such a solution include enablingfor storing transaction audit trails in a blockchain in a way that theaudit trail stored in the blockchain may not reveal any informationabout the transaction and that any of the blockchain entities may not beable to store several trails for the same transaction.

The blockchain ledger data is immutable and that provides traceabilityand provenance with regard transactions and performance of theblockchain. Also, use of the blockchain provides security and buildstrust. The smart contract also manages the state of the asset tocomplete the life-cycle. The example blockchain is permissiondecentralized. Hence, each host device may have a ledger copy to access.Additionally, multiple Organizations (and peers) may be on-boarded onthe blockchain network. The key Organizations may serve as endorsingpeers to validate the smart contract execution results, read-set andwrite-set. The exemplary blockchain may be integrated with mobileapplications or browser-based applications.

Blockchain is different from a traditional database in that blockchainis not a central storage, but rather a decentralized, immutable, andsecure storage, where nodes must share in changes to records in thestorage. Some properties that are inherent in blockchain and which helpimplement the blockchain include, but are not limited to, an immutableledger, smart contracts, security, privacy, decentralization, consensus,endorsement, accessibility, and the like, which are further describedherein. According to various aspects, the system for generation ofunfalsifiable audit logs in blockchains is implemented due to immutableaccountability, security, privacy, permitted decentralization,availability of smart contracts, endorsements and accessibility that areinherent and unique to blockchain. In particular, the blockchain ledgerdata is immutable and that provides for efficient method of storingtransaction audit trails in a blockchain in a way that the audit trailstored in the blockchain may not reveal any information about thetransaction and that any of the blockchain entities may not be able tostore several trails for the same transaction. Also, use of theencryption in the blockchain provides security and builds trust. Thesmart contract manages the state of the asset to complete thelife-cycle. The example blockchains are permission decentralized. Thus,each end user may have its own ledger copy to access. MultipleOrganizations (and peers) may be on-boarded on the blockchain network.The key Organizations may serve as endorsing peers to validate the smartcontract execution results, read-set and write-set. In other words, theblockchain inherent features provide for efficient storing of theunfalsifiable transaction audit trails.

One of the benefits of the example embodiments is an improvement of thefunctionality of a computing system by providing access to capabilitiessuch as distributed ledger, peers, encryption technologies, MSP, eventhandling, etc. Also, the blockchain enables to create a business networkand make any users or organizations to on-board for participation. Assuch, the blockchain is not just a database. The blockchain comes withcapabilities to create a Business Network of users andon-board/off-board organizations to collaborate and execute serviceprocesses in the form of smart contracts.

Through the blockchain solution described herein, a computing system canperform novel functionality by providing an automated method forgeneration of unfalsifiable audit logs and for storing these logs in theblockchain.

The example embodiments provide numerous benefits over a traditionaldatabase. For example, various advantages are achieved by immutableaccountability, security, privacy, permitted decentralization,availability of smart contracts, endorsements and accessibility that areinherent and unique to blockchain.

Meanwhile, a traditional database could not be used to implement theexample embodiments, because it does not bring all parties on thebusiness network, it does not create trusted collaboration and does notprovide for efficient storage of unfalsifiable audit logs. Thetraditional database does not provide for a tamper proof storage anddoes not provide for unfalsifiable nature of the audit logs. Thus, theproposed method for generation and storage of unfalsifiable audit logscannot be implemented in the traditional database.

Meanwhile, if a traditional database were to be used to implement theexample embodiments, the example embodiments would have suffered fromunnecessary drawbacks such as search capability, lack of security andslow speed of transactions. Additionally, the automated method forgeneration and storage of unfalsifiable audit logs would simply not bepossible.

Accordingly, the example embodiments provide for a specific solution toa problem in the arts/field of efficient storing and auditingtransactions. In particular, the exemplary embodiments provide for anautomated method for generation and storage of unfalsifiable audit logsin a blockchain.

FIG. 1 illustrates a system for generation and storage of unfalsifiableaudit logs in a blockchain, according to example embodiments. Referringto FIG. 1, the example network 100 includes a participating node 102connected to a blockchain 106, which has a blockchain ledger 108 forstoring transaction trails 107. While this example shows only oneparticipating node 102, multiple such nodes may be connected to theblockchain 106. It should be understood that the participating node 102may include additional components and that some of the componentsdescribed herein may be removed and/or modified without departing from ascope of the participating node 102 disclosed herein. The participatingnode 102 may be a computing device or a server computer, or the like,and may include a processor 104, which may be a semiconductor-basedmicroprocessor, a central processing unit (CPU), an application specificintegrated circuit (ASIC), a field-programmable gate array (FPGA),and/or another hardware device. Although a single processor 104 isdepicted, it should be understood that the participating node 102 mayinclude multiple processors, multiple cores, or the like, withoutdeparting from a scope of the participating node 102 system.

The participating node 102 may also include a non-transitory computerreadable medium 112 that may have stored thereon machine-readableinstructions executable by the processor 104. Examples of themachine-readable instructions are shown as 114-122 and are furtherdiscussed below. Examples of the non-transitory computer readable medium112 may include an electronic, magnetic, optical, or other physicalstorage device that contains or stores executable instructions. Forexample, the non-transitory computer readable medium 112 may be a RandomAccess memory (RAM), an Electrically Erasable Programmable Read-OnlyMemory (EEPROM), a hard disk, an optical disc, or other type of storagedevice.

The processor 104 may fetch, decode, and execute the machine-readableinstructions 114 to connect to a blockchain 106. The blockchain 106 maybe managed by one or more devices and may be accessible by multipleparticipating nodes on a decentralized network. The blockchain 106 maybe configured to use one or more smart contracts that producetransaction trails 107 for multiple participating nodes. The blockchain106 may have a ledger 108, which contains the transaction trails 107 andaudit logs. The transaction trails 107 may reflect transactions executedby the participating node 102.

The processor 104 may fetch, decode, and execute the machine-readableinstructions 116 to execute a transaction to produce a transaction trail107. The processor 104 may fetch, decode, and execute themachine-readable instructions 118 to assign a transaction identifier(ID) to the transaction. The processor 104 may fetch, decode, andexecute the machine-readable instructions 120 to generate a transactiontag based on the transaction ID. The processor 104 may fetch, decode,and execute the machine-readable instructions 122 to send, to theblockchain 106, the transaction tag along with the transaction trail tobe entered into the blockchain ledger 108.

According to one exemplary embodiment, the protocol implemented by theparticipating node 102 may be as follows. Two hash functions H1 and H2(e.g., random oracles) may be used. The players of the protocol areparticipating parties (i.e., nodes) running the blockchain 106. Pi arethe parties that log the transactions 107 and Ai are the auditors.

Each logging party Pi generates a public key. Using a discrete log basedsystem, the party Pi may choose a random x and then compute the publickey as y=g{circumflex over ( )}x, where g is group generator. Then, tolog a trail Tr for a transaction Tid, the Pi may compute atag=H1(Tid){circumflex over ( )}x and a commitment to the trail ascTr=H2(Tr, H2(Tid){circumflex over ( )}x), and then record a pair (tag,cTr) on the blockchain. When the auditor Ai wants to audit a transactionTid, the logging party Pi may provide the values tag′=H1(Tid){circumflexover ( )}x, Tr, and u=H2(Tid){circumflex over ( )}x to the auditor Ai.Then, the Pi may further prove to the Ai that the x used to compute thetag′ and u is indeed its secret key, e.g., using the following proofprotocol (in Camenisch-Stadler notation):

-   -   PK{(x): y=g{circumflex over ( )}x AND tag′=H1(Tid){circumflex        over ( )}x AND u=H2(Tid){circumflex over ( )}x}        Once the auditor Ai has verified this proof, the Ai may check        whether (tag′, H2(Tr, u)) is stored in the blockchain 106,        whether there is no other pair (tag′, Ctr*) for any Ctr* stored        in the blockchain 106. If this is the case, the Tr is indeed the        correct transaction trail for the transaction Tid. For better        long term protection, double bases may be used—i.e.,        y=g{circumflex over ( )}xh{circumflex over ( )}z and then the        tags may be computed as H1(0/Tid){circumflex over ( )}x        H1(1/Tid){circumflex over ( )}z, etc.

FIG. 2A illustrates a blockchain architecture configuration 200,according to example embodiments. Referring to FIG. 2A, the blockchainarchitecture 200 may include certain blockchain elements, for example, agroup of blockchain nodes 202. The blockchain nodes 202 may include oneor more nodes 204-210 (these nodes are depicted by example only). Thesenodes participate in a number of activities, such as blockchaintransaction addition and validation process (consensus). One or more ofthe blockchain nodes 204-210 may endorse transactions and may provide anordering service for all blockchain nodes in the architecture 200. Ablockchain node may initiate a blockchain authentication and seek towrite to a blockchain immutable ledger stored in blockchain layer 216, acopy of which may also be stored on the underpinning physicalinfrastructure 214. The blockchain configuration may include one orapplications 224 which are linked to application programming interfaces(APIs) 222 to access and execute stored program/application code 220(e.g., chaincode, smart contracts, etc.) which can be created accordingto a customized configuration sought by participants and can maintaintheir own state, control their own assets, and receive externalinformation. This can be deployed as a transaction and installed, viaappending to the distributed ledger, on all blockchain nodes 204-210.

The blockchain base or platform 212 may include various layers ofblockchain data, services (e.g., cryptographic trust services, virtualexecution environment, etc.), and underpinning physical computerinfrastructure that may be used to receive and store new transactionsand provide access to auditors which are seeking to access data entries.The blockchain layer 216 may expose an interface that provides access tothe virtual execution environment necessary to process the program codeand engage the physical infrastructure 214. Cryptographic trust services218 may be used to verify transactions such as asset exchangetransactions and keep information private.

The blockchain architecture configuration of FIG. 2A may process andexecute program/application code 220 via one or more interfaces exposed,and services provided, by blockchain platform 212. The code 220 maycontrol blockchain assets. For example, the code 220 can store andtransfer data, and may be executed by nodes 204-210 in the form of asmart contract and associated chaincode with conditions or other codeelements subject to its execution. As a non-limiting example, smartcontracts may be created to execute reminders, updates, and/or othernotifications subject to the changes, updates, etc. The smart contractscan themselves be used to identify rules associated with authorizationand access requirements and usage of the ledger. For example, thetransaction tag information 226 may be processed by one or moreprocessing entities (e.g., virtual machines) included in the blockchainlayer 216. The result 228 may include the transaction audit logcorresponding to the transaction tag. The physical infrastructure 214may be utilized to retrieve any of the data or information describedherein.

Within chaincode, a smart contract may be created via a high-levelapplication and programming language, and then written to a block in theblockchain. The smart contract may include executable code, which isregistered, stored, and/or replicated with a blockchain (e.g.,distributed network of blockchain peers). A transaction is an executionof the smart contract code, which can be performed in response toconditions associated with the smart contract being satisfied. Theexecuting of the smart contract may trigger a trusted modification(s) toa state of a digital blockchain ledger. The modification(s) to theblockchain ledger caused by the smart contract execution may beautomatically replicated throughout the distributed network ofblockchain peers through one or more consensus protocols.

The smart contract may write data to the blockchain in the format ofkey-value pairs. Furthermore, the smart contract code can read thevalues stored in a blockchain and use them in application operations.The smart contract code can write the output of various logic operationsinto the blockchain. The code may be used to create a temporary datastructure in a virtual machine or other computing platform. Data writtento the blockchain can be public and/or can be encrypted and maintainedas private. The temporary data that is used/generated by the smartcontract is held in memory by the supplied execution environment, thendeleted once the data needed for the blockchain is identified.

A chaincode may include the code interpretation of a smart contract,with additional features. As described herein, the chaincode may beprogram code deployed on a computing network, where it is executed andvalidated by chain validators together during a consensus process. Thechaincode receives a hash and retrieves from the blockchain a hashassociated with the data template created by use of a previously storedfeature extractor. If the hashes of the hash identifier and the hashcreated from the stored identifier template data match, then thechaincode sends an authorization key to the requested service. Thechaincode may write to the blockchain data associated with thecryptographic details. In FIG. 2A, the transaction tag request mayresult in a transaction audit trail reflecting committed transactions.One function may be to retrieve the transaction trail from theblockchain corresponding to the transaction tag that may be provided toone or more of the nodes 204-210.

FIG. 2B illustrates an example of a transactional flow 250 between nodesof the blockchain in accordance with an example embodiment. Referring toFIG. 2B, the transaction flow may include a transaction proposal 291sent by an application client node 260 to an endorsing peer node 281.The endorsing peer 281 may verify the client signature and execute achaincode function to initiate the transaction. The output may includethe chaincode results, a set of key/value versions that were read in thechaincode (read set), and the set of keys/values that were written inchaincode (write set). The proposal response 292 is sent back to theclient 260 along with an endorsement signature, if approved. The client260 assembles the endorsements into a transaction payload 293 andbroadcasts it to an ordering service node 284. The ordering service node284 then delivers ordered transactions as blocks to all peers 281-283 ona channel. Before committal to the blockchain, each peer 281-283 mayvalidate the transaction. For example, the peers may check theendorsement policy to ensure that the correct allotment of the specifiedpeers have signed the results and authenticated the signatures againstthe transaction payload 293.

Referring again to FIG. 2B, the client node 260 initiates thetransaction 291 by constructing and sending a request to the peer node281, which is an endorser. The client 260 may include an applicationleveraging a supported software development kit (SDK), such as NODE,JAVA, PYTHON, and the like, which utilizes an available API to generatea transaction proposal. The proposal is a request to invoke a chaincodefunction so that data can be read and/or written to the ledger (i.e.,write new key value pairs for the assets). The SDK may serve as a shimto package the transaction proposal into a properly architected format(e.g., protocol buffer over a remote procedure call (RPC) and take theclient's cryptographic credentials to produce a unique signature for thetransaction proposal.

In response, the endorsing peer node 281 may verify (a) that thetransaction proposal is well formed, (b) the transaction has not beensubmitted already in the past (replay-attack protection), (c) thesignature is valid, and (d) that the submitter (client 260, in theexample) is properly authorized to perform the proposed operation onthat channel. The endorsing peer node 281 may take the transactionproposal inputs as arguments to the invoked chaincode function. Thechaincode is then executed against a current state database to producetransaction results including a response value, read set, and write set.However, no updates are made to the ledger at this point. In 292, theset of values, along with the endorsing peer node's 281 signature ispassed back as a proposal response 292 to the SDK of the client 260,which parses the payload for the application to consume.

In response, the application of the client 260 inspects/verifies theendorsing peers signatures and compares the proposal responses todetermine if the proposal response is the same. If the chaincode onlyqueried the ledger, the application would inspect the query response andwould typically not submit the transaction to the ordering node service284. If the client application intends to submit the transaction to theordering node service 284 to update the ledger, the applicationdetermines if the specified endorsement policy has been fulfilled beforesubmitting (i.e., did all peer nodes necessary for the transactionendorse the transaction). Here, the client may include only one ofmultiple parties to the transaction. In this case, each client may havetheir own endorsing node, and each endorsing node will need to endorsethe transaction. The architecture is such that even if an applicationselects not to inspect responses or otherwise forwards an unendorsedtransaction, the endorsement policy will still be enforced by peers andupheld at the commit validation phase.

After successful inspection, in step 293 the client 260 assemblesendorsements into a transaction and broadcasts the transaction proposaland response within a transaction message to the ordering node 284. Thetransaction may contain the read/write sets, the endorsing peerssignatures and a channel ID. The ordering node 284 does not need toinspect the entire content of a transaction in order to perform itsoperation, instead the ordering node 284 may simply receive transactionsfrom all channels in the network, order them chronologically by channel,and create blocks of transactions per channel.

The blocks of the transaction are delivered from the ordering node 284to all peer nodes 281-283 on the channel. The transactions 294 withinthe block are validated to ensure any endorsement policy is fulfilledand to ensure that there have been no changes to ledger state for readset variables since the read set was generated by the transactionexecution. Transactions in the block are tagged as being valid orinvalid. Furthermore, in step 295 each peer node 281-283 appends theblock to the channel's chain, and for each valid transaction the writesets are committed to current state database. An event is emitted, tonotify the client application that the transaction (invocation) has beenimmutably appended to the chain, as well as to notify whether thetransaction was validated or invalidated.

FIG. 3 illustrates an example of a permissioned blockchain network 300,which features a distributed, decentralized peer-to-peer architecture,and a certificate authority 318 managing user roles and permissions. Inthis example, the blockchain user 302 may submit a transaction to thepermissioned blockchain network 310. In this example, the transactioncan be a deploy, invoke or query, and may be issued through aclient-side application leveraging an SDK, directly through a REST API,or the like. Trusted business networks may provide access to regulatorsystems 314, such as auditors (the Securities and Exchange Commission ina U.S. equities market, for example). Meanwhile, a blockchain networkoperator system of nodes 308 manage member permissions, such asenrolling the regulator system 310 as an “auditor” and the blockchainuser 302 as a “client.” An auditor could be restricted only to queryingthe ledger whereas a client could be authorized to deploy, invoke, andquery certain types of chaincode.

A blockchain developer system 316 writes chaincode and client-sideapplications. The blockchain developer system 316 can deploy chaincodedirectly to the network through a REST interface. To include credentialsfrom a traditional data source 330 in chaincode, the developer system316 could use an out-of-band connection to access the data. In thisexample, the blockchain user 302 connects to the network through a peernode 312. Before proceeding with any transactions, the peer node 312retrieves the user's enrollment and transaction certificates from thecertificate authority 318. In some cases, blockchain users must possessthese digital certificates in order to transact on the permissionedblockchain network 310. Meanwhile, a user attempting to drive chaincodemay be required to verify their credentials on the traditional datasource 330. To confirm the user's authorization, chaincode can use anout-of-band connection to this data through a traditional processingplatform 320.

FIG. 4A illustrates a flow diagram 400 of an example method ofgeneration of unfalsifiable audit logs for a blockchain, according toexample embodiments. Referring to FIG. 4A, the method 400 may includeone or more of the steps described below.

FIG. 4A illustrates a flow chart of an example method executed by theparticipating node 102 (see FIG. 1). It should be understood that method400 depicted in FIG. 4A may include additional operations and that someof the operations described therein may be removed and/or modifiedwithout departing from the scope of the method 400. The description ofthe method 400 is also made with reference to the features depicted inFIG. 1 for purposes of illustration. Particularly, the processor 104 ofthe participating node 102 may execute some or all of the operationsincluded in the method 400.

With reference to FIG. 4A, at block 412, the processor 104 may connectto a blockchain 106 configured to store transactions executed by theparticipating node 102. At block 414, the processor 104 may execute atransaction to produce a transaction trail 107. At block 416, theprocessor 104 may assign a transaction identifier (ID) to thetransaction. At block 418, the processor 104 may generate a transactiontag based on the transaction ID. At block 420, the processor 104 maysend, to the blockchain 106, the transaction tag along with thetransaction trail to be entered into the blockchain 106.

FIG. 4B illustrates a flow diagram 450 of an example method ofprocessing of the transaction tag for a transaction trail to be enteredinto a blockchain, according to example embodiments. Referring to FIG.4B, the method 450 may also include one or more of the following steps.At block 452, the processor 104 may apply a keyed one-way function tothe transaction ID to generate the transaction tag. At block 454, theprocessor 104 may encrypt the transaction trail. At block 456, theprocessor 104 may store the transaction trail using theoretic hidingcommitments. At block 458, the processor 104 may associate thetransaction tag with the transaction ID based on cryptographiczero-knowledge proof.

FIG. 5A illustrates an example physical infrastructure configured toperform various operations on the blockchain in accordance with one ormore of the example methods of operation according to exampleembodiments. Referring to FIG. 5A, the example configuration 500includes a physical infrastructure 510 with a blockchain 520 and a smartcontract 530, which may execute any of the operational steps 512included in any of the example embodiments. The steps/operations 512 mayinclude one or more of the steps described or depicted in one or moreflow diagrams and/or logic diagrams. The steps may represent output orwritten information that is written or read from one or more smartcontracts 530 and/or blockchains 520 that reside on the physicalinfrastructure 510 of a computer system configuration. The data can beoutput from an executed smart contract 530 and/or blockchain 520. Thephysical infrastructure 510 may include one or more computers, servers,processors, memories, and/or wireless communication devices.

FIG. 5B illustrates an example smart contract configuration amongcontracting parties and a mediating server configured to enforce thesmart contract terms on the blockchain according to example embodiments.Referring to FIG. 5B, the configuration 550 may represent acommunication session, an asset transfer session or a process orprocedure that is driven by a smart contract 530 which explicitlyidentifies one or more user devices 552 and/or 556. The execution,operations and results of the smart contract execution may be managed bya server 554. Content of the smart contract 630 may require digitalsignatures by one or more of the entities 552 and 556 which are partiesto the smart contract transaction. The results of the smart contractexecution may be written to a blockchain as a blockchain transaction.

The above embodiments may be implemented in hardware, in a computerprogram executed by a processor, in firmware, or in a combination of theabove. A computer program may be embodied on a computer readable medium,such as a storage medium. For example, a computer program may reside inrandom access memory (“RAM”), flash memory, read-only memory (“ROM”),erasable programmable read-only memory (“EPROM”), electrically erasableprogrammable read-only memory (“EEPROM”), registers, hard disk, aremovable disk, a compact disk read-only memory (“CD-ROM”), or any otherform of storage medium known in the art.

An exemplary storage medium may be coupled to the processor such thatthe processor may read information from, and write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor. The processor and the storage medium may reside in anapplication specific integrated circuit (“ASIC”). In the alternative,the processor and the storage medium may reside as discrete components.For example, FIG. 6 illustrates an example computer system architecture600, which may represent or be integrated in any of the above-describedcomponents, etc.

FIG. 6 is not intended to suggest any limitation as to the scope of useor functionality of embodiments of the application described herein.Regardless, the computing node 600 is capable of being implementedand/or performing any of the functionality set forth hereinabove.

In computing node 600 there is a computer system/server 602, which isoperational with numerous other general purpose or special purposecomputing system environments or configurations. Examples of well-knowncomputing systems, environments, and/or configurations that may besuitable for use with computer system/server 602 include, but are notlimited to, personal computer systems, server computer systems, thinclients, thick clients, hand-held or laptop devices, multiprocessorsystems, microprocessor-based systems, set top boxes, programmableconsumer electronics, network PCs, minicomputer systems, mainframecomputer systems, and distributed cloud computing environments thatinclude any of the above systems or devices, and the like.

Computer system/server 602 may be described in the general context ofcomputer system-executable instructions, such as program modules, beingexecuted by a computer system. Generally, program modules may includeroutines, programs, objects, components, logic, data structures, and soon that perform particular tasks or implement particular abstract datatypes. Computer system/server 602 may be practiced in distributed cloudcomputing environments where tasks are performed by remote processingdevices that are linked through a communications network. In adistributed cloud computing environment, program modules may be locatedin both local and remote computer system storage media including memorystorage devices.

As shown in FIG. 6, computer system/server 602 in cloud computing node600 is shown in the form of a general-purpose computing device. Thecomponents of computer system/server 602 may include, but are notlimited to, one or more processors or processing units 604, a systemmemory 606, and a bus that couples various system components includingsystem memory 606 to processor 604.

The bus represents one or more of any of several types of busstructures, including a memory bus or memory controller, a peripheralbus, an accelerated graphics port, and a processor or local bus usingany of a variety of bus architectures. By way of example, and notlimitation, such architectures include Industry Standard Architecture(ISA) bus, Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA)bus, Video Electronics Standards Association (VESA) local bus, andPeripheral Component Interconnects (PCI) bus.

Computer system/server 602 typically includes a variety of computersystem readable media. Such media may be any available media that isaccessible by computer system/server 602, and it includes both volatileand non-volatile media, removable and non-removable media. System memory606, in one embodiment, implements the flow diagrams of the otherfigures. The system memory 606 can include computer system readablemedia in the form of volatile memory, such as random-access memory (RAM)610 and/or cache memory 612. Computer system/server 602 may furtherinclude other removable/non-removable, volatile/non-volatile computersystem storage media. By way of example only, storage system 614 can beprovided for reading from and writing to a non-removable, non-volatilemagnetic media (not shown and typically called a “hard drive”). Althoughnot shown, a magnetic disk drive for reading from and writing to aremovable, non-volatile magnetic disk (e.g., a “floppy disk”), and anoptical disk drive for reading from or writing to a removable,non-volatile optical disk such as a CD-ROM, DVD-ROM or other opticalmedia can be provided. In such instances, each can be connected to thebus by one or more data media interfaces. As will be further depictedand described below, memory 606 may include at least one program producthaving a set (e.g., at least one) of program modules that are configuredto carry out the functions of various embodiments of the application.

Program/utility 616, having a set (at least one) of program modules 618,may be stored in memory 606 by way of example, and not limitation, aswell as an operating system, one or more application programs, otherprogram modules, and program data. Each of the operating system, one ormore application programs, other program modules, and program data orsome combination thereof, may include an implementation of a networkingenvironment. Program modules 618 generally carry out the functionsand/or methodologies of various embodiments of the application asdescribed herein.

As will be appreciated by one skilled in the art, aspects of the presentapplication may be embodied as a system, method, or computer programproduct. Accordingly, aspects of the present application may take theform of an entirely hardware embodiment, an entirely software embodiment(including firmware, resident software, micro-code, etc.) or anembodiment combining software and hardware aspects that may allgenerally be referred to herein as a “circuit,” “module” or “system.”Furthermore, aspects of the present application may take the form of acomputer program product embodied in one or more computer readablemedium(s) having computer readable program code embodied thereon.

Computer system/server 602 may also communicate with one or moreexternal devices 620 such as a keyboard, a pointing device, a display622, etc.; one or more devices that enable a user to interact withcomputer system/server 602; and/or any devices (e.g., network card,modem, etc.) that enable computer system/server 602 to communicate withone or more other computing devices. Such communication can occur viaI/O interfaces 624. Still yet, computer system/server 602 cancommunicate with one or more networks such as a local area network(LAN), a general wide area network (WAN), and/or a public network (e.g.,the Internet) via network adapter 626. As depicted, network adapter 626communicates with the other components of computer system/server 602 viaa bus. It should be understood that although not shown, other hardwareand/or software components could be used in conjunction with computersystem/server 602. Examples, include, but are not limited to: microcode,device drivers, redundant processing units, external disk drive arrays,RAID systems, tape drives, and data archival storage systems, etc.

Although an exemplary embodiment of at least one of a system, method,and non-transitory computer readable medium has been illustrated in theaccompanied drawings and described in the foregoing detaileddescription, it will be understood that the application is not limitedto the embodiments disclosed, but is capable of numerous rearrangements,modifications, and substitutions as set forth and defined by thefollowing claims. For example, the capabilities of the system of thevarious figures can be performed by one or more of the modules orcomponents described herein or in a distributed architecture and mayinclude a transmitter, receiver or pair of both. For example, all orpart of the functionality performed by the individual modules, may beperformed by one or more of these modules. Further, the functionalitydescribed herein may be performed at various times and in relation tovarious events, internal or external to the modules or components. Also,the information sent between various modules can be sent between themodules via at least one of: a data network, the Internet, a voicenetwork, an Internet Protocol network, a wireless device, a wired deviceand/or via plurality of protocols. Also, the messages sent or receivedby any of the modules may be sent or received directly and/or via one ormore of the other modules.

One skilled in the art will appreciate that a “system” could be embodiedas a personal computer, a server, a console, a personal digitalassistant (PDA), a cell phone, a tablet computing device, a Smartphoneor any other suitable computing device, or combination of devices.Presenting the above-described functions as being performed by a“system” is not intended to limit the scope of the present applicationin any way but is intended to provide one example of many embodiments.Indeed, methods, systems and apparatuses disclosed herein may beimplemented in localized and distributed forms consistent with computingtechnology.

It should be noted that some of the system features described in thisspecification have been presented as modules, in order to moreparticularly emphasize their implementation independence. For example, amodule may be implemented as a hardware circuit comprising custom verylarge-scale integration (VLSI) circuits or gate arrays, off-the-shelfsemiconductors such as logic chips, transistors, or other discretecomponents. A module may also be implemented in programmable hardwaredevices such as field programmable gate arrays, programmable arraylogic, programmable logic devices, graphics processing units, or thelike.

A module may also be at least partially implemented in software forexecution by various types of processors. An identified unit ofexecutable code may, for instance, comprise one or more physical orlogical blocks of computer instructions that may, for instance, beorganized as an object, procedure, or function. Nevertheless, theexecutables of an identified module need not be physically locatedtogether but may comprise disparate instructions stored in differentlocations which, when joined logically together, comprise the module andachieve the stated purpose for the module. Further, modules may bestored on a computer-readable medium, which may be, for instance, a harddisk drive, flash device, random access memory (RAM), tape, or any othersuch medium used to store data.

Indeed, a module of executable code could be a single instruction, ormany instructions, and may even be distributed over several differentcode segments, among different programs, and across several memorydevices. Similarly, operational data may be identified and illustratedherein within modules and may be embodied in any suitable form andorganized within any suitable type of data structure. The operationaldata may be collected as a single data set or may be distributed overdifferent locations including over different storage devices, and mayexist, at least partially, merely as electronic signals on a system ornetwork.

It will be readily understood that the components of the application, asgenerally described and illustrated in the figures herein, may bearranged and designed in a wide variety of different configurations.Thus, the detailed description of the embodiments is not intended tolimit the scope of the application as claimed but is merelyrepresentative of selected embodiments of the application.

One having ordinary skill in the art will readily understand that theabove may be practiced with steps in a different order, and/or withhardware elements in configurations that are different than those whichare disclosed. Therefore, although the application has been describedbased upon these preferred embodiments, it would be apparent to those ofskill in the art that certain modifications, variations, and alternativeconstructions would be apparent.

While preferred embodiments of the present application have beendescribed, it is to be understood that the embodiments described areillustrative only and the scope of the application is to be definedsolely by the appended claims when considered with a full range ofequivalents and modifications (e.g., protocols, hardware devices,software platforms, etc.) thereto.

What is claimed is:
 1. A method, comprising: connecting, by aparticipating node, to a blockchain configured to store transactionsexecuted by the participating node; executing, by the participatingnode, a transaction to produce a transaction trail; assigning, by theparticipating node, a transaction identifier (ID) to the transaction;generating, by the participating node, a transaction tag based on thetransaction ID; and sending to the blockchain, by the participatingnode, the transaction tag and the transaction trail to be entered intothe blockchain.
 2. The method of claim 1, further comprising applying akeyed one-way function to the transaction ID to generate the transactiontag.
 3. The method of claim 1, further comprising encrypting thetransaction trail.
 4. The method of claim 1, further comprising storingthe transaction trail using theoretic hiding commitments.
 5. The methodof claim 1, wherein the transaction ID is unique to the transaction andto the participating node.
 6. The method of claim 1, further comprisingassociating the transaction tag with the transaction ID based oncryptographic zero-knowledge proof.
 7. The method of claim 6, whereinthe transaction tag serves as a proof of a single transaction trailassociated with the transaction ID.
 8. A system, comprising: aprocessor; a memory on which are stored machine readable instructionsthat when executed by the processor, cause the processor to: connect toa blockchain configured to store transactions executed by aparticipating node; execute a transaction to produce a transactiontrail; assign a transaction identifier (ID) to the transaction; generatea transaction tag based on the transaction ID; and send, to theblockchain, the transaction tag and the transaction trail to be enteredinto the blockchain.
 9. The system of claim 8, wherein the instructionsare further to cause the processor to apply a keyed one-way function tothe unique transaction ID to generate the transaction tag.
 10. Thesystem of claim 8, wherein the instructions are further to cause theprocessor to encrypt the transaction trail.
 11. The system of claim 8,wherein the instructions are further to cause the processor to store thetransaction trail by the use of theoretic hiding commitments.
 12. Thesystem of claim 8, wherein the transaction ID is unique to thetransaction and to the participating node.
 13. The system of claim 8,wherein the instructions are further to cause the processor to associatethe transaction tag with the transaction ID based on a cryptographiczero-knowledge proof.
 14. The system of claim 8, wherein the transactiontag serves as a proof of a single transaction trail associated with thetransaction ID.
 15. A non-transitory computer readable medium comprisinginstructions, that when read by a processor of a participating node,cause the processor to perform: connecting to a blockchain configured tostore transactions executed by the participating node; executing atransaction to produce a transaction trail; assigning a transactionidentifier (ID) to the transaction; generating a transaction tag basedon the transaction ID; and sending to the blockchain the transaction tagand the transaction trail to be entered into the blockchain.
 16. Thenon-transitory computer readable medium of claim 15, further comprisinginstructions, that when read by the processor, cause the processor toapply a keyed one-way function to the unique transaction ID to generatethe transaction tag.
 17. The non-transitory computer readable medium ofclaim 15, further comprising instructions, that when read by theprocessor, cause the processor to encrypt the transaction trail.
 18. Thenon-transitory computer readable medium of claim 15, wherein theinstructions are further to cause the processor to store the transactiontrail using theoretic hiding commitments.
 19. The non-transitorycomputer readable medium of claim 15, wherein the instructions arefurther to cause the processor to associate the transaction tag with thetransaction ID based on a cryptographic zero-knowledge proof.
 20. Thenon-transitory computer readable medium of claim 15, wherein thetransaction tag serves as a proof of a single transaction trailassociated with the transaction ID.